Search

A chemical equilibrium model was developed to predict the product composition of a biomass gasification system using highly preheated air and steam. The advantages and limitations of this system were discussed from a thermodynamic viewpoint. The first and second law analyses have been conducted for various preheating temperatures and steam/biomass mass (S/B) ratios. The results demonstrated that the chemical energy output of the produced syngas is highest when the S/B ratio is 1.83 under the conditions used in this study. However, higher S/B ratios have a negative effect on the energy and exergy efficiencies. Higher preheating temperatures increase the chemical energy of the produced syngas and the two efficiencies. The peak values for the energy and exergy efficiencies are 81.5% and 76.2%, respectively. Based on the calculated limitation values, where the highest chemical energy (exergy) of the produced syngas and maximum achievable efficiencies are determined, a thermodynamically possible operating region is suggested. [ABSTRACT FROM AUTHOR]

Experimental research on the pyrolysis and gasification of randomly packed straw pellets was conducted with an emphasis on the reactive properties of the shrinking porous structure of the pellets. The apparent kinetics of such pyrolysis was approximated by the random pore, grain, and volumetric models. The best approximation results were obtained with the grain and random pore models. The self-organized oscillations of the pellet conversion rate during pyrolysis were observed. Two complementary explanations of the phenomenon are proposed. [ABSTRACT FROM AUTHOR]

The article discusses the influence of oxide scale on heat transfer during reheating of steel. It presents methodology and development of a mathematical model for prediction of the influence of oxide scale on heat transfer during reheating of steel in an industrial furnace. Using the model, temperatures inside the steel billet were measured and with thermocouples at selected places and were collected by a water cooled computer that was traveling inside the slab.

The article discusses a study which examines transient surface temperature, heat flux and effective heat transfer coefficient of a steel slab heated in an industrial reheating furnace. A model for inverse heat conduction is used to calculate the transient surface temperature, heat flux and effective heat transfer coefficient.